Lung cancer is commonly found in small cell lung cancer and non-small cell lung cancer, the latter mainly including adenocarcinoma, squamous carcinoma, large cell carcinoma and mixed lung cancer. Small cell lung cancer includes limited stage and extensive stage. The limited stage requires radical radiotherapy to the chest, and it is currently believed that the use of chest radiotherapy in the extensive stage can improve survival. Stage I and II non-small cell lung cancers do not require thoracic radiotherapy after surgery, but require additional radiotherapy if the stump is positive. If patients with stage I NSCLC cannot tolerate surgery or do not undergo surgery, they can be treated with stereotactic radiotherapy (radiation knife such as X-blade) with overall survival similar to that of surgery.